Precooking apparatus

ABSTRACT

An apparatus for precooking chicken or other food products which are to be reheated by frying prior to consumption. The product is provided with a coating or breading, and is placed in a perforated tray to be conveyed through a tank holding a shallow bath of heated cooking oil. The depth of the bath is controlled so only the lowermost portion of the product makes direct contact with oil, and so the tray or pan has no tendency to float in the bath while being conveyed through the tank. Alternatively, the perforated tray is placed in a solid pan which carries a very shallow layer of cooking oil, and the solid pan is conveyed through the tank. The product is tenderized and the coating is converted to a protective shield by the hot, humid air above the oil and surrounding the product as it is conveyed through the bath. The precooked product and tray are removed from the bath and permitted to drain and cool prior to packaging.

States atent Stanley J. Simmons 408 Latone, Monrovia, Calif. 91016 [72]Inventor [211 App]. No. 687,881 [22] Filed Dec. 4, 1967 [45] PatentedSept. 14, 1971 [54] PRECOOKING APPARATUS 5 Claims, 7 Drawing Figs.

[52] US. Cl 99/404 [51] Int. Cl A47j 37/00 [50] Field Search 99/107,

OTHER REFERENCES Also considered, 3,460,462 99- 404, 2,807,203 99- 404,2,616,359 99- 408, 1,236,405 99 404, 3,152,537 99- 404, 3,446,138 99-404, 1,209,811 Fr. 99- 404.

Primary ExaminerWalter A. Scheel Assistant Examiner-Leon G. MachlinAn0rneyChristie, Parker and Hale ABSTRACT: An apparatus for precookingchicken or other food products which are to be reheated by frying priorto consumption. The product is provided with a coating or breading, andis placed in a perforated tray to be conveyed through a tank holding ashallow bath of heated cooking oil. The depth of the bath is controlledso only the lowermost portion of the product makes direct contact withoil, and so the tray or pan has no tendency to float in the bath whilebeing conveyed through the tank. Alternatively, the perforated tray isplaced in a solid pan which carries a very shallow layer of cooking oil,and the solid pan is conveyed through the tank. The product istenderized and the coating is converted to a protective shield by thehot, humid air above the oil and surrounding the product as it isconveyed through the bath. The precooked product and tray are removedfrom the bath and permitted to drain and cool prior to packaging.

PATENTED SEPI 41911 SHEET 2 BF 2 INVIL'N'I'OR. 'm/l/z 5/ J 2 /244045PRECOOKING APPARATUS BACKGROUND OF THE INVENTION The food industry hasin recent years developed various precooked products which are madeready for consumption by a relatively quick reheating and perhaps finalcooking. These products are especially attractive to restaurants asprolonged preparation is avoided, and the food can be made ready forprompt service. The precooked products are typically capable ofrelatively long term storage in frozen form.

Some precooked foods such as chicken have a coating or breading appliedto the outer surfaces thereof. The coating helps to prevent loss ofnatural juices in the food during cooking, and is also sometimes used toimpart flavor or color to the cooked product. Flour is a desirablecoating for chicken, but other materials can also be used such asbatters made of eggs, milk, and flour, or similar mixtures to whichbread or cereal crumbs can be added.

Precooking in the past has usually been in deep-fat fryers, but boiling,stewing and pressure-cooking techniques have also been used.Conventional pan frying is too slow and cumbersome if reasonableproduction rates and costs are to be achieved. Boiling, stewing andpressure cooking are not especially satisfactory for coated productssuch as chicken because the coating must be applied after completion ofthe precooking process. Natural juices and flavor are lost from the foodduring precooking, and an adhesive or bonding agent such as milk solids,eggs, or the like must be used to insure adherence of the coating to theproduct. These factors, plus the shrinkage and extra labor required forcoating application, have made the deep-fat fryer the most popularprecooking method for coated products.

Precooking of coated products by deep-fat frying has several importantdeficiencies. First, a relatively heavy breading-type coating must beused to prevent erosion and dissipation of the coating when the productis submerged in boiling oil or fat. This type of coating leads to asecond problem which is excessive absorption of cooking oil or fat inthe coated product. When the precooked food is substantially reheated orfinish cooked, there is an undesirable taste which arises from theexcessive retention of cooking oil from the precooking process.Precooking by deep-fat frying has thus been less than satisfactory dueto the loss of a wholesome, fresh taste and, particularly in the case ofchicken, a deterioration of the delicate flavor normally associated witha freshly prepared product.

The apparatus of this invention overcome the deficiencies of precookingby deep-fat frying, and pen'nit precooking of coated products such aschickens at high production rates and low processing cost. The productis prepared with a simple coating such as plain flour, and is thenplaced in a metal tray having a perforated floor. The tray is thenplaced in a conveyor-type oven where it is drawn through a shallow bathof heated cooking oil. The depth of the bath is controlled such thatonly the lowermost portions of the chicken in the tray are in directcontact with the cooking oil.

The tray is slowly conveyed through a covered zone in the oven, andprecooking is accomplished by heat transferred from the hot bottom ofthe tank, and from a hot, humid atmosphere which surrounds the chicken.When precooking is complete, the chicken and tray are removed from theoven and allowed to cool. The chicken can thereafter be left in theperforated tray, and subsequently processed by the usual steps of quickchilling, wrapping, and deep freezing to be ready for marketing.

Precooking can also be accomplished by placing the chicken or similarcoated product on a perforated sheet or tray which is in turn placed ina solid open-topped pan which carries a layer of cooking oil aboutone-sixteenth to oneeighth inch in depth. The solid pan is in turnconveyed through the shallow bath of heated oil in the tank. Thisapproach has the advantage that juices dripping from the product duringprecooking are trapped in the solid pan, and the resulting mixture ofoil and juices provides an excellent base for subsequent preparation ofa natural gravy. Furthermore, the useful life of oil in the tank isappreciably extended as this oil is not mixed with juices from theproduct.

The precooked product has a thin coating which has not been submerged incooking oil, and excessive absorption of oil and consequentdeterioration of taste is therefore avoided. When the product is finishcooked by quickly frying just prior to serving, it will have atenderness, color and flavor which closely resembles that of freshlyprepared food.

SUMMARY OF THE INVENTION Briefly stated, the apparatus of this inventionis a conveyortype cooker for precooking a food product such as chicken.The cooker comprises an elongated frame with a tank secured thereto andadapted to contain a shallow bath of cooking oil. The tank includesmeans for limiting the depth of the cookingoil bath to less than about1/4 inch. A food-product tray is disposed in and rests on the tank. Thetray has a perforated bottom whereby the lowermost portion of the foodproduct is in contact with the cooking oil. Conveying means are providedfor moving the tray through the tank, and heating means maintain thecooking oil at an elevated temperature. Preferably, the cooker isprovided with a plurality of domed covers adapted to be positioned alongand over the cooking-oil tank whereby the tank is substantially coveredexcept at its entrance and exit ends where openings adequate to provideclearance for the tray and product are provided.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described indetail with reference to the attached drawings, in which:

FIG. 1 is a side elevation of a conveyor cooker according to theinvention;

FIG. 2 is a view along line 2-2 of FIG. 1;

FIG. 3 is a view along line 33 of FIG. 1;

FIG. 4 is a view along line 4-4 of FIG. 1;

FIG. 5 is a sectional side view of a perforated tray carrying a piece ofchicken to be precooked;

FIG. 6 is a sectional side view of a perforated tray carried in a solidpan which is conveyed through the cooker; and

FIG. 7 is a top view ofthe tray and pan shown in FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to thedrawings, a conveyor oven 10 according to the invention includes anelongated upright frame 11 having conventional legs 12 and supportingcross members 13. The

lower part of the oven is partially enclosed by a pair of I sidewalls l4and a bottom wall 15. The sidewalls have lower edges which arepositioned slightly above the bottom wall to provide access to aplurality of drip pans l6 resting on the bottom wall.

A shallow, elongated tank 20 for cooking oil is secured at the upper endof the frame. Each side of the tank has an outwardly turned lip 21, anda plurality of domed covers 22 rest on these lips. The ends of the tankare upwardly sloped as best seen in FIG. 1, and the bottom of the tankin the sloping portions is corrugated (FIG. 4) to permit rapid drainageof oil from trays emerging from the oven. A shallow bath of cooking oil23 is disposed in the bottom of tank 20, and preferably has a depth ofabout one-eighth inch. The maximum depth of the cooking-oil bath islimited to no more than about one-quarter inch by any convenient meanssuch as overflow outlet holes 24 extending through the sides of the tankand positioned about one-fourth inch above the floor of the tank.Lengths of tubing 25 are secured to the sides of the tank incommunication with the outlet holes, and these tubes direct any overflowcooking oil from the tank to drip pans 16. A conventional drip feeder(not shown) can be used with the oven to supply fresh oil to the tank.

A conveyor system moves through tank 20, and includes a pair oflaterally spaced roller chains 30 which pass over and are engaged by aseries of cogwheels 31 secured to the frame. A conventionalvariable-speed drive motor 32 is coupled to the chains through thecogwheels, and the motor continuously drives the chains through thetank. As best seen in FIG. 1, the chains emerge from the tank and followa return path under the tank just above the drip pans.

A plurality of longitudinally spaced bars 35 are secured to and extendbetween carrier chains 30, and a pair of wheels 36 are mounted onopposite ends of each bar 35. The wheels ride on the floor of tank 20,and prevent the chains from dragging in the shallow layer of cookingoil. A plurality of rollers 37 extend from opposite sides of the tank tomaintain tension in the chain and insured that the chain is guided alongthe desired path.

A heating means, such as a plurality of electrical heaters 40, ispositioned under tank 20 and is secured to the oven frame. The heatersare thermostatically controlled by conventional means (not shown) andare coupled to a power source through conventional wiring (not shown).Gas burners may of course be substituted for the electrical heaters ifdesired. heaters are thermostatically controlled by conventional means(not shown) and are coupled to a power source through conventionalwiring (not shown). Gas burners may of course be substituted for theelectrical heaters if desired.

Products such as chicken parts 44 to be precooked in the oven areconveyed through the tank of cooking oil in a plurality of trays 45which are preferably about inches wide, 21 inches long, and ill; incheshigh. The trays are formed from light-gage metal such as aluminum, andinclude perforations or holes 46 through their bottom walls. The traysare placed in the tank between bars 35, and are pulled by the barsthrough the tank by operation of the conveyor system. Conventionalendless-belt conveyors may be used to insert and withdraw trays from theconveyor oven, and an entrance conveyor 48 and an exit conveyor 49 areshown in schematic form in FIG. I.

l have found that the conveyor oven operates most satisfactorily withproducts such as coated chicken when the vertical spacing between thefloor of tank and the top of dome covers 22 is about 3 to 3% inches.This spacing has been found to be proper for maintaining the correctdegree and amount of hot, humid atmosphere around the product to becooked. A shorter spacing results in excessively intense heating of thechicken and a consequent loss of natural juices, and larger spacingcauses an excessively long cooking cycle and otherwise detracts from thequality of the precooked product. The scalloped surface presented by theserially arranged dome covers 22 retards the flow of hot, humid airtoward the ends of the oven such that loss of this atmosphere isminimized.

Tank 20 is preferably about 22 inches wide, and is preferably formedfrom a material such as cast aluminum of about one-eighth inchthickness, but other materials such as cast iron are also suitablethough more difficult to clean. The oven has an overall length of about24 feet and tank 20 has a horizontal surface about 20 feet in length topermit a relatively long cooking cycle of about 30 minutes forconveyance of the products through the oven.

Operation of the oven will be described in terms of its use with chickenas the oven has been found to be particularly suitable for precookingthis type of product. Chicken parts are cleaned and prepared in theusual manner, and while still moist from rinsing, the parts are lightlyseasoned. The stillmoist parts are then shaken gently in a flour bath tobe covered with a light flour coating over their entire outer surfaces.The coated chicken parts are then placed on perforated trays 45 withtheir boney sides down. This orientation is preferred as it places aminimum amount of skin in contact with the tray.

The trays are then loaded at the entrance end of the oven and areprewarmed as they are conveyed down the inclined entrance to the cookingtank. when the trays reach the level portion of tank 20, they come incontact with the shallow bath of cooking oil which has been heated toabout 265 F. to 270 F. The hot cooking oil flows through holes 46 in thefloor or bottom wall of each tray, but the oil contacts only the verylowermost part of the chicken as the depth of the cooking-oil bath islimited as described above. That is, the oil extends only to about thelevel of the upper surface of the tray bottom, and only a very smallportion of the chicken is in direct contact with the cooking oil.

The oil is heated to a temperature sufficient to cause vaporization, andthe atmosphere substantially enclosed by the tank and domed covers ishot and very humid as it is at least partially saturated with oil vapor.The combination of conductive heat received from the tray and convectiveheating from this hot atmosphere serves to thoroughly tenderize thechicken and to form a protective shield out of the original dryflourcoating. The coating serves to retard the loss of natural juices duringthe cooking period. The factors of slow heating, humid atmosphere, andthe coating combine to prevent the chicken from becoming dry, andpatching of the coating (as typically occurs with dry heat) is alsoprevented. it has been found that the coating does not become watery orsoggy as is often experienced when steam cooking techniques are usedwith coated products.

At the end of the cooking cycle, the trays are conveyed up the exit endof the conveyor oven. As they move slowly up the inclined ramp at theexit end, oil drains from the bottom of the trays and is returned to thebank. The chicken has been kept relatively free from absorption ofcooking oil or fat during the cooking cycle, and is ready for coolingfor about 30 minutes in preparation for freezing, packaging, or otherprocessing prior to storage.

When the product is ready to be consumed, it is reheated and cooked byfrying. Chicken is quickly cooked either in a conventional frying pan inabout 6 minutes per side at medium heat, or for about 6 to 7 minutes ina conventional deep-fat fryer operating at about 360 F. The finalproduct has a taste closely resembling freshly cooked chicken andlacking the offensive oil flavor which is retained in heavily breadedchicken as precooked in a deep-frying process.

It is most important to use perforated trays in this process, andparticularly essential to limit the depth of the cooking oil to littlemore than a thin film which extends just through the floor of the trayto contact only the lowermost parts of the chicken. I have found thatthe depth of the oil bath should not exceed about one-fourth of an inch,as depths in excess of this value tend to cause excessive dissipationand breakdown of the coating, as well as undesired oil absorption andcarryover. The bath, however, should have a depth sufficient topenetrate through the floor of the trays. Experiments with unperforatedtrays without a thin bath of oil or cooking fat therein have generallybeen unsatisfactory as the cooked chicken is overly dry and lacks thetender texture which characterizes chicken cooked in perforated trays.

An alternative technique for conveying chicken or similar coatedproducts through the cooker is shown in FIGS. 6 and 7. Chicken parts 55are positioned in a thin perforated tray 56 which may be identical totray 45 or may simply be a perforated flat sheet of metal or foil (notshown). An important function of the tray is to facilitate handling ofthe product without damage to the thin coating (especially immediatelyafter emergence from the oven while the coating is still hot andrelatively fragile), and to permit quick draining and cooling. in caseswhere the precooked product is packaged with the tray for delivery tothe ultimate consumer, the tray also serves as a useful carrier for usein final deep-frying of the product.

Tray 56 is placed in an open-top solid pan 57 which carries a thin filmor bath of cooking oil 58, the depth of which does not exceed aboutone-sixteenth to one-eighth inch. Pan 57 has sides 59 which arepreferably about 1 inch in height. The pan is in turn conveyed throughtank 20 which, as described above, contains a shallow bath of cookingoil which has a depth no greater than about one-fourth inch and isheated to about 265 F. to 270 F. When the pan emerges from the cooker,tray 56 is removed and, if desired, can be packaged with the precookedproduct.

During precooking, some juices escape from the chicken parts, and thesejuices pass through the perforations in the tray to be trapped in pan57. The mixture of juices and the thin layer of fresh oil in the pan canbe recovered to provide an excellent base from which gravy for theproduct is subsequently prepared. Contamination of the main oil bath intank is also prevented as juices from the product are prevented fromdripping into the tank by pan 57. The useful life of the oil is therebyconsiderably extended, and the oil is maintained in a clean, wholesomecondition.

In both of the techniques described above, successful operation ispredicted on the use of a perforated tray (which may be a flat sheet, ora sheet with upturned sides) to carry the product, and a shallow bath ofcooking oil which directly contacts only the very lowermost part of theproduct. Control of the bath depth is also important to avoid anyflotation of the pan or tray. Flotation is undesirable as it appears toaffect a desirable conduction of heat directly from the tank bottom intothe tray or pan. In any event, total immersion of the product in theheated oil is always avoided, and the undesirable carryover or retentionof cooking oil in the product is minimized.

There has been described a novel cooking apparatus which is suitable forprecooking products having only a thin coating to retain natural juicesand flavor. The apparatus has been found to be most useful with chicken,and has been described in terms of that application. The apparatus,however, is not limited to this use, and is satisfactory with othertypes of food products.

What is claimed is:

l. A conveyor cooker for precooking a food product such as chicken,comprising:

a frame;

a tank secured to the frame and adapted to contain a shallow bath ofcooking oil, the tank including means for limiting the depth of thecooking-oil bath to less than about one-fourth inch;

a food-product tray disposed in and resting on the tank, the tray havinga perforated bottom whereby oil in the tank reaches an upper surface ofthe tray bottom to contact only lowermost portions of a food product inthe tray, and portions of the product above the lowermost portions areisolated from direct immersion in the oil by the tank depth-limitingmeans;

conveying means for moving the tray through the tank; and

heating means for maintaining the cooking oil at an elevatedtemperature.

2. The cooker defined in claim 1, and further comprising a plurality ofdomed covers adapted to be positioned along and over the cooking-oiltank whereby the tank is substantially covered except at its entranceand exit ends.

3. The cooker defined in claim 2 in which the domed covers and tank arespaced to define an enclosure having a height of about 3 to 3% inches.

4. A conveyor cooker for precooking a food product such as chicken,comprising a frame;

an elongated tank secured to the frame and adapted to contain a shallowbath of cooking oil, the tank including means for limiting the depth ofthe bath to less than about one-fourth inch;

a solid, open-top pan disposed in and resting on the tank, the pan beingadapted to hold a thin layer of cooking oil;

a food-product tray disposed in and resting on the pan, the tray havinga perforated bottom whereby oil in the pan reaches an upper surface ofthe tray bottom to contact lowermost portions of a food product in thetray;

conveying means for moving the pan through the tank; and

heating means for maintaining the cooking oil at an elevatedtemperature.

5. The cooker defined in claim 4, and further comprising a plurality ofdomed covers adapted to be positioned along and over the cooking-oiltank whereby the tank is substantially covered except at its entranceand exist ends.

Po-ww UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent3,604,340 -Dated September 14, 1971 Inventor) Stanley J. Simmons It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

I- Column 1, line 41, "substantially" should read subsequently- Column'3, line 15 "insured" should read --insure--;

lines 23 through 26 delete "heaters are thermostatically controlled byconventional means (not shown) and are coupled to a power source throughconventional wiring (not shown) Gas burners may of course be substitutedfor the electrical heaters if desired."

Colunm 4, line 35, after "and" insert --finish--.

Column 5, line 16 "predicted" should read --predicated--.

Signed and sealed this 18th day of April 1972.

(SEAL) Attost:

EDWARD M.FLE'I'CHER,JR. ROBERT GOT'I'SCHALK At testing Officer- JCommissioner of Patents

1. A conveyor cooker for precooking a food product such as chicken,comprising: a frame; a tank secured to the frame and adapted to containa shallow bath of cooking oil, the tank including means for limiting thedepth of the cooking-oil bath to less than about one-fourth inch; afood-product tray disposed in and resting on the tank, the tray having aperforated bottom whereby oil in the tank reaches an upper surface ofthe tray bottom to contact only lowermost portions of a food product inthe tray, and portions of the product above the lowermost portions areisolated from direct immersion in the oil by the tank depth-limitingmeans; conveying means for moving the tray through the tank; and heatingmeans for maintaining the cooking oil at an elevated temperature.
 2. Thecooker defined in claim 1, and further comprising a plurality of domedcovers adapted to be positioned along and over the cooking-oil tankwhereby the tank is substantially covered except at its entrance andexit ends.
 3. The cooker defined in claim 2 in which the domed coversand tank are spaced to define an enclosure having a height of about 3 to3 1/2 inches.
 4. A conveyor cooker for precooking a food product such aschicken, comprising a frame; an elongated tank secured to the frame andadapted to contain a shallow bath of cooking oil, the tank includingmeans for limiting the depth of the bath to less than about one-fourthinch; a solid, open-top pan disposed in and resting on the tank, the panbeing adapted to hold a thin layer of cooking oil; a food-product traydisposed in and resting on the pan, the tray having a perforated bottomwhereby oil in the pan reaches an upper surface of the tray bottom tocontact lowermost portions of a food product in the tray; conveyingmeans for moving the pan through the tank; and heating means formaintaining the cooking oil at an elevated temperature.
 5. The cookerdefined in claim 4, and further comprising a plurality of domed coversadapted to be positioned along and over the cooking-oil tank whereby thetank is substantially covered except at its entrance and exist ends.